you should accept "peter" as well as "Peter". I knew I had the right answer but it wouldn't allow it until I capitalised the name. I know it's a name and should be capitalised, but I was trying to save time against the time limit.
I'm quite sure the Queen was not the Duchess of Edinburgh because the monarch cannot have any lesser titles. She was though the Duchess of Edinburgh between 1947 and 1952 before becoming Queen.